Digital cameras can be used to identify objects and to determine the orientations and locations of the objects. Imaging objects from different camera locations may be used to determine distances to the objects and the configuration of the objects in 3D. An example of a stereoscopic camera that is sometimes used for such applications is the BUMBLEBEE™ camera system available from Point Grey Research of Richmond, British Columbia, Canada.
Performing stereo image processing to determine the location of points on an object in 3D requires knowledge of the locations and orientations of the cameras used to acquire the images. It is desirable in an imaging system to be used for stereoscopic imaging that the relative locations and orientations of the imaging chips be fixed or at least known at all times so that the stereo camera system can be calibrated once and thereafter used to accurately determine the location of points on objects within its field of view.
Changes in temperature can cause thermal expansion and contraction of different parts of a 3D imaging system. The expansion and contraction may result in forces moving the imaging chip orientations out of their original pointing directions or positions, resulting in lost calibration.
There is a need for reliable and cost effective stereoscopic camera systems which avoid inaccuracies due to thermal expansion and contraction.